1. Field of the Invention
The invention relates to a vehicle on which an engine (internal combustion engine) and an electric motor are mounted as driving power sources and which includes a power split mechanism in a powertrain, and a control method for the vehicle.
2. Description of Related Art
There is a hybrid vehicle, as an example of a vehicle, that includes an engine, a first electric motor (first motor generator MG1), a power split mechanism (planetary gear mechanism) and a second electric motor (second motor generator). The first electric motor is able to input or output power. The power split mechanism includes three rotating elements, that is, a sun gear, a ring gear arranged concentrically with the sun gear and a planetary carrier that supports pinion gears meshed with those sun gear and ring gear such that the pinion gears are rotatable and revolvable. The second electric motor is able to input or output power to drive wheels. An output shaft (crankshaft) of the engine is coupled to the planetary carrier among the three rotating elements of the power split mechanism. A rotary shaft of the first electric motor is coupled to the sun gear. The drive wheels are coupled to the ring gear.
In the thus configured hybrid vehicle, an engine operation range is set in consideration of the durability of the engine and gears, and the like, of the powertrain (for example, see Japanese Patent Application Publication No. 2010-264852 (JP 2010-264852 A) and Japanese Patent Application Publication No. 2012-046053 (JP 2012-046053 A)). With the technique described in the above publications, the engine operation range is set to a range in which the rotation speed (number of revolutions) of the pinion gears that rotate due to a difference in rotation between the sun gear and the ring gear does not exceed an allowable rotation speed (limit value) in a high engine rotation and low vehicle speed range, and the engine operation range is similarly limited in a low engine rotation and high vehicle speed range.